Apparatus and method for bend-shaping a glass sheet

ABSTRACT

An apparatus for bend-shaping a glass sheet is disclosed, which comprises a heating furnace, a plurality of in-furnace beds disposed within the heating furnace, at least one out-furnace bed disposed externally of the heating furnace proximately to an outlet of the heating furnace, and an elevating mechanism disposed below that one of the in-furnace beds which is positioned proximately to the outlet and the out-furnace bed. The in- and out-furnace beds have upper surfaces curved transversely and capable of jetting air to floatingly support a glass sheet. For producing a dual curved glass sheet, the elevating mechanism is operated to elevate opposed ends of the one in-furnace bed and the out-furnace bed so that these beds jointly form a hill. For producing a single-curved glass sheet, the elevating mechanism is operated to lower the opposed ends of those beds to their original flat positions.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an apparatus and method forbend-shaping a glass sheet into a bi-directionally curved shape.

[0003] 2. Description of the Prior Art

[0004] Many glass sheets for use as automobile side windows are bent inonly one direction (hereinafter referred to as “single-curved glasssheet”). Such glass sheets are known from, for example, Japanese PatentPublication No. SHO-43-11768 entitled “METHOD OF TRANSFERRRING HEATBETWEEN A GLASS SHEET AND GASES FLOWING IN CONTACT WITH THE SHEET”(corresponding to U.S. Pat. No. 3,332,759 and No. 3,332,760).

[0005] For design reasons, such side window glass sheets are oftenrequired to be bent in two directions, namely, a first direction and asecond direction normal to the first direction (hereinafter referred toas “dual-curved glass sheet” and often as “complexly-curved glasssheet”). An apparatus for bend-shaping such a complexly-curved glasssheet is proposed in, for example, Japanese Patent Laid-Open PublicationNo. HEI-5-009037 “METHOD AND APPARATUS FOR BEND-SHAPING A GLASS SHEET”(corresponding to U.S. Pat. No. 6,014,873). An overall arrangement ofthe proposed apparatus is schematically illustrated in FIG. 15 hereof.

[0006] As shown in FIG. 15, the proposed apparatus includes a heatingfurnace 150 having an array of beds 151 (only one shown) positionedtherein. Air is jetted from upper surfaces 151 a of the beds 151 tofloatingly support a glass sheet 153 for successively transferring, viaa transfer means not shown, the glass sheet 153 over the upper surfaces151 a of the beds 151 in an arrowed direction.

[0007] Toward an outlet 150 a of the heating furnace 150, the uppersurfaces 151 a of the beds 151 gradually become curved in a transversedirection (normal to a direction of transfer of the glass sheet 153) sothat they have an upwardly convex shape. Thus, as the glass sheet 153 istransferred over the upper surfaces 151 a in the arrowed direction, theglass sheet is gradually bent by its own weight (self-sagging) into ashape complementary with the shape of the beds 151 to thereby provide asingle-curved glass sheet.

[0008] After arrival at a position proximate to the outlet 150 a of theheating furnace 150, the single-curved glass sheet 153 advancesinclinedly upwardly over beds 155, 156 disposed within the heatingfurnace (hereinafter called “in-furnace beds”) in an upwardly inclinedfashion. These beds 155, 156 have respective upper surfaces 155 a, 156 acurved not only in a transverse direction but also in the direction oftransfer of the glass sheet. Thus, transfer of the single-curved glasssheet 153 over those beds 155, 156 causes the glass sheet 153 to becomea complexly-curved glass sheet which is bent in both transverse andtransfer directions of the glass sheet 153.

[0009] Continuously, the complexly-curved glass sheet 153 is transferredto a cooling bed 160 positioned proximately to and externally of theoutlet 150 a of the heating furnace 150 (hereinafter called “out-furnacebed”), where, while being supported by air jetted from an upper surface160 a of the out-furnace bed 160 in a floated fashion, thecomplexly-curved glass sheet 153 is cooled by cooling air jetted fromcooling means 162 positioned upwardly of the glass sheet 153.

[0010] Reference is made next to FIG. 16 illustrating a conventionalin-furnace bed on an enlarged scale.

[0011] Upper surface 156 a of the in-furnace bed 156 is curved both in adirection of its width W and in a direction of its length L. The uppersurface 156 a of the in-furnace bed 156 has a multiplicity of air jetholes 157. Air is jetted from the air jet holes 157 to floatinglysupport the single-curved glass sheet 153 over the upper surface 156 a,whereupon the glass sheet 153 is bent also in the direction of transferof the glass sheet to thereby provide the desired dual-curved glasssheet.

[0012] Similarly to the upper surface 156 a of the in-furnace bed 156,the upper surface 160 a of the out-furnace bed 160 shown in FIG. 15 iscurved both in a transverse direction and in a direction of transfer ofthe glass sheet.

[0013] Apart from the publication just described, an apparatus forbend-shaping a glass sheet into a dual-curved shape is also disclosed inJapanese Patent Laid-Open Publication No. HEI-6-191867 (U.S. Pat. No.5,522,912). In the apparatus of this publication, a final bed disposedin heating furnace is curved in a transverse direction but is linear ina direction of transfer of a glass sheet. The final bed has an uppersurface of uphill shape, that is, uprising toward an outlet of theheating furnace. In contrast, a quenching bed disposed externally of theheating furnace has an upper surface of downhill shape. Upon transferfrom the final bed onto the quenching bed, the glass sheet is formedinto a dual-curved glass sheet.

[0014] Another method and apparatus for bend-shaping a glass sheet isdisclosed in Japanese Patent Laid-Open Publication No. HEI-9-202633.This publication teaches jetting hot air downwardly and combining adownward force produced by the jetted hot air with the weight of a glasssheet being bent to thereby facilitate bending of the glass sheet. As aresult, the time required for bending a glass sheet can be shortened.Further, the hot air is jetted downwardly through a gap between aninclined bed and a cooling bed to provide an air curtain which keepscooling air away from the glass sheet to thereby maintain the glasssheet at its softening temperature.

[0015] It is costly to install two lines of manufacture, namely, one formanufacturing the single-curved glass sheet, as described above, and theother for manufacturing the dual-curved glass sheet, as also describedabove. If a single line of manufacture is made available for use inproducing both the single-curved glass sheet and dual-curved glasssheet, this will achieve substantial cost reduction.

[0016] For example, the in-furnace beds 155, 156 of the bend-shapingapparatus disclosed in Japanese Patent Laid-Open Publication No.HEI-5-009037, discussed with reference to FIG. 15, may be replaced withnew beds 151, 151 curved only in a transverse direction, while theout-furnace bed 160 may be replaced with a bed curved only in atransverse direction. This makes the bend-shaping apparatus availablefor use in manufacturing a single-curved glass sheet.

[0017] Thus, only the bend-shaping apparatus as shown in FIG. 15 may beinstalled for manufacturing a single-curved glass sheet. When desired,relevant parts of the apparatus may be substituted by other parts tomanufacture a dual-curved glass sheet. However, this involves tediousoperations to switch the apparatus from one mode of operation to anotherby replacing the beds for manufacturing a single-curved glass sheet withthe beds 155, 156 for manufacturing a dual-curved glass sheet.

[0018] Further, upon changing the beds for manufacturing thesingle-curved glass sheet to the beds 155, 156 for manufacturing thedual-curved glass sheet, it is necessary to lower the temperature of theheating furnace from about 700° C. (glass softening temperature) to anatmospheric temperature. In addition, after the beds for manufacturingthe single-curved glass sheet to the beds 155, 156 for manufacturing thedual-curved glass sheet, the temperature within the furnace 150 must berisen to about 700° C. again. Consequently, bed changing takes arelatively long time, thereby deteriorating productivity. Moreover, itis necessary to provide two different types of beds, namely, beds 155,156, 160 for manufacturing the dual-curved glass sheet and beds forbending the glass sheet, thereby increasing the cost of glass sheetproduction.

SUMMARY OF THE INVENTION

[0019] It is therefore an object of the present invention to provide anapparatus and a method for bend-shaping a glass sheet, which is capableof increasing productivity and reducing installation costs.

[0020] According to one aspect of the present invention, there isprovided an apparatus for bend-shaping a glass sheet, which comprises: aheating furnace for heating the glass sheet, transferred therethroughalong a path of travel thereof, to a substantially softening temperatureof the glass sheet, the heating furnace having an inlet positionedupstream of the path of travel and an outlet positioned downstream ofthe path of travel; a plurality of in-furnace beds disposed within theheating furnace, each of the in-furnace beds having an upper surface ofupwardly convex shape with a curvature increasing progressively towardthe outlet of the heating furnace, the upper surfaces being designed tojet hot air against the glass sheet to support the glass sheet in afloated state thereover such that the glass sheet bends transversely byits own weight complementarily to the shape of the upper surfaces; atleast one out-furnace bed disposed externally of the heating furnaceproximately to the outlet of the heating furnace, the out-furnace bedhaving an upper surface of upwardly convex shape, the in-furnace bedsand the out-furnace bed being arranged linearly along the path oftravel; and an elevating mechanism, disposed below a downstream end ofthat one of the in-furnace beds which is positioned proximately to theoutlet of the heating furnace and below an upstream end of theout-furnace bed, for elevating the downstream end of the one in-furnacebed and the upstream end of the out-furnace bed to cause the onein-furnace bed and the out-furnace bed to form a hill sloped in adirection along the path of travel, so that upon passage over the hill,the glass sheet bends longitudinally by its own weight complementarilyto the shape of the hill, the upper surface of the out-furnace bed beingdesigned to jet cold air against the glass sheet transferred past theoutlet of the heating furnace to cool down the glass sheet whilesupporting the same in a floated state thereover.

[0021] By operating the elevating mechanism, the degree of inclinationof the uphill formed by the one in-furnace bed and of the downhillformed by the out-furnace bed can be adjusted. Consequently, thedual-curved glass sheet can be readily produced by a simple operation toarrange the one in-furnace bed and the out-furnace bed to form the hill.With the one in-furnace bed and out-furnace bed returned to theiroriginal flat positions by operating the elevating mechanism, thebend-shaping apparatus can also be used for bend-shaping a single-curvedglass sheet. Stated otherwise, the bend-shaping apparatus as arrangedabove enables production of both the single-curved glass sheet anddual-curved glass sheet without requiring changing of the beds but bysimply causing the one in-furnace bed and the out-furnace bed to beinclined in such a manner as to form the hill. In addition, the beds forproducing the single-curved glass sheet can also be used for producingthe dual-curved glass sheet. This leads to the advantage that switchingfrom one mode for the production of the single-curved glass sheet toanother mode for the production of the dual-curved glass sheet becomesunnecessary.

[0022] Desirably, the bend-shaping apparatus further comprises a slidemechanism for sliding at least one of the one in-furnace bed and theout-furnace bed in the direction along the path of travel of the glasssheet. Provision of the slide mechanism makes it possible to move theone in-furnace bed and the out-furnace bed toward one another so that agap defined between the downstream end of the one in-furnace bed and theupstream end of the out-furnace bed when these beds are arranged to formthe hill can be kept to a minimum. This leads to the advantage that theglass sheet can be transferred smoothly from the one in-furnace bed tothe out-furnace bed.

[0023] Preferably, the one in-furnace bed has a downstream end surfaceof curved configuration, while the out-furnace bed has an upstream endsurface of curved configuration. This enables the downstream end surfaceof the one in-furnace bed and the upstream end surface of theout-furnace bed to come closer to each other when those beds arearranged to form the hill, thereby further narrowing the gap between thedownstream end surface of the one in-furnace bed and the upstream endsurface of the out-furnace bed.

[0024] Alternatively, the downstream end surface of the one in-furnacebed may have a lower corner while the upstream end surface of theout-furnace bed may have a lower corner, at least one of which lowercorners is chamfered. This also enables the downstream end surface ofthe one in-furnace bed and the upstream end surface of the out-furnacebed to come closer to each other so that the gap defined between thoseend surfaces when the one in-furnace bed and the out-furnace bed arearranged to form the hill can be kept to a minimum.

[0025] In a preferred form, the bend-shaping apparatus further includesa guide roll, disposed in the space defined between the one in-furnacebed and the out-furnace bed, for guiding the glass sheet along the pathof travel. This makes it possible to smoothly transfer the glass sheetpulled past the outlet of the heating furnace onto the out-furnace bed.

[0026] The guide roll may have a curved configuration conforming to thecurved shape of the glass sheet so that the glass sheet can be supportedin its entire transverse area by the roll, thereby facilitating smoothtransfer of the glass sheet onto the out-furnace.

[0027] The bend-shaping apparatus may further includes an air jetnozzle, disposed in the space defined between the one in-furnace bed andthe out-furnace bed, for jetting air against the glass sheet to therebyguide the latter along the path of travel. The air jetted from the airjet nozzle makes up for that part of a force for floating the glasssheet that may be lost by arranging the one in-furnace bed and theout-furnace bed in the hill form (inverted V-shape).

[0028] According to another aspect of the present invention, there isprovided a method for bend-shaping a glass sheet in a bend-shapingapparatus including a heating furnace having an outlet positioneddownstream of a path of transfer of the glass sheet, a plurality ofin-furnace beds disposed within the heating furnace, at least oneout-furnace bed disposed externally of the heating furnace proximatelyto the outlet in end to end relation to that one of the in-furnace bedswhich is positioned proximately to the outlet, the in-furnace beds andthe out-furnace bed having upper surfaces curved transversely, themethod comprising the steps of: elevating a downstream end of the onein-furnace bed and an upstream end of the out-furnace bed to apredetermined bed inclination height H so that the one in-furnace bedand the out-furnace bed jointly form a hill which allows to impart adesired radius of curvature C to the glass sheet, the bed inclinationheight H being obtained by first determining a first relation betweenthe bed inclination height H and an apparent bed radius of curvature Ron a basis of a length L1 of the one in-furnace bed forming an uphill ofthe hill, a length L2 of the out-furnace bed forming a downhill of thehill, the bed inclination height H, and a length G of the glass sheet ina direction of transfer thereof, and then determining a second relationbetween the apparent bed radius of curvature R and the radius ofcurvature C of the glass sheet; heating the glass sheet in the heatingfurnace to a substantially softening temperature of the glass sheet andjetting hot air from the upper surfaces of the in-furnace beds tofloatingly support the glass sheet in such a manner as to allow theglass sheet to bend by own weight thereof transversely complementarilyto the shape of the transversely curved in-furnace beds; transferringthe transversely bent glass sheet over the hill so that the glass sheetbends longitudinally complementarily to the shape of the hill sloped inthe direction of transfer; and transferring the bi-directionally bentglass sheet past the outlet onto the out-furnace bed and jetting coldair from the upper surface of the out-furnace bed to cool thebi-directionally bent glass sheet while floatingly supporting thelatter.

[0029] By virtue of the hill sloped in the direction of transfer, theglass sheet can be bent in the direction of its transfer upon transferof the glass sheet over the hill. Further, since the interrelationsbetween the bed inclination height H, apparent bed radius of curvatureR, and glass sheet radius of curvature C are pre-determined, the bedinclination height H can be readily obtained from such interrelations.If it were not for such interrelations, the operation to bend the glasssheet in the direction of its transfer becomes tedious and timeconsuming because repeated adjustments of the bed inclination height Hbecome inevitable and the glass sheet must be checked to see if it has adesired radius of curvature after each adjustment.

[0030] Desirably, curvature (1/C) represented as a reciprocal of theglass sheet radius of curvature C falls in a range of 0<(1/C)<1×10⁻⁴mm⁻¹. 0<(1/C) is used herein because the glass sheet radius of curvatureC becomes infinite when (1/C)=0, resulting in the production of asingle-curved glass sheet linear in the direction of its transfer. Thus,0<(1/C) is required for the production of a dual-curved glass sheet. Thereason for the adoption of (1/C)<1×10⁻⁴ mm⁻¹ is that if (1/C)≧1×10⁻⁴mm⁻¹ is used in its stead, the glass sheet radius of curvature C becomessmaller than 1×10⁴ mm. This makes the bed inclination too excessive andsmooth transfer of the glass sheet difficult to achieve. There is also afear that the lower surface of the glass sheet may be scratched byinterfering with the beds laid in an angled fashion. Further, it mayalso become difficult to smoothly bend the glass sheet in the directionof its transfer. Thus, the vertical movement of the beds is restrictedto (1/C)<1×10⁻⁴ mm⁻¹. As a result, the glass sheet can be prevented frombeing damaged at a lower surface thereof during its transfer over thehill.

[0031] In a preferred form, the relation between the apparent bed radiusof curvature R and the glass sheet radius of curvature C is representedby the expression: R=0.43×C+12.8×10³ (unit: mm). From this expression,the apparent bed radius of curvature can be readily obtained.

[0032] The cooling of the glass sheet over the out-furnace bed maycomprise air quenching the glass sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Certain preferred embodiments of the present invention will bedescribed in detail below, byway of example only, with reference to theaccompanying drawings, in which:

[0034]FIG. 1 is a perspective view illustrating the overall arrangementof a bend-shaping apparatus according to a first embodiment of thepresent invention;

[0035]FIG. 2 is an exploded perspective view showing, on an enlargedscale, an out-furnace bed and a second elevating mechanism of theapparatus shown in FIG. 1;

[0036]FIGS. 3A and 3B are side elevational views showing a first phaseof a bend-shaping method according to the present invention;

[0037]FIGS. 4A and 4B are side elevational views showing a second phaseof the bend-shaping method;

[0038]FIG. 5 is a side elevational view showing a third phase of thebend-shaping method;

[0039]FIG. 6 is a schematic side elevational view showing the dimensionsof component parts of the bend-shaping apparatus;

[0040]FIG. 7 is a graph illustrating a relation between an apparent bedradius of curvature and a bed inclination height when a bed length is750 mm;

[0041]FIG. 8 is a graph showing a relation between the apparent bedradius of curvature and bend inclination height when the bed length is1,000 mm;

[0042]FIG. 9 is a graph showing a relation between the apparent bedradius of curvature and a glass sheet radius of curvature;

[0043]FIGS. 10A and 10B are schematic views showing relevant parts of abend-shaping apparatus according to a second embodiment of the presentinvention;

[0044]FIG. 11 is a schematic side elevational view showing relevantparts of a bend-shaping apparatus according to a third embodiment of thepresent invention;

[0045]FIG. 12 is a schematic side elevational view showing relevantparts of a bend-shaping apparatus according to a fourth embodiment ofthe present invention;

[0046]FIG. 13 is a schematic side elevational view showing relevantparts of a bend-shaping apparatus according to a fifth embodiment of thepresent invention;

[0047]FIG. 14 is a schematic side elevational view showing relevantparts of a bend-shaping apparatus according to a sixth embodiment of thepresent invention;

[0048]FIG. 15 is a schematic side elevational view showing aconventional bend-shaping apparatus; and

[0049]FIG. 16 is a schematic perspective view showing a conventionalin-furnace bed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] The following description is merely exemplary in nature and is inno way intended to limit the invention, its application or uses.

[0051] Referring to FIG. 1, an apparatus 10 for bend-shaping a glasssheet, according to the present invention, comprises a heating furnace11 for heating a glass sheet 18 to a glass softening temperature, aplurality of in-furnace beds 12 (only one shown) positioned within theheating furnace 11 between an inlet (not shown) and an outlet 11 a ofthe furnace 11, and a separate in-furnace bed 15 positioned next to adownstream end one of the in-furnace beds 12 and proximately to theheating furnace outlet 11 a.

[0052] The in-furnace beds 12, 15 have respective upper surfaces 13, 16of upwardly convex shape, whose curvatures increase gradually toward theoutlet 11 a of the heating furnace 11.

[0053] Hot air is jetted from the upper surfaces 13, 16 of thein-furnace beds 12, 15 to floatingly support the glass sheet 18. Whilebeing held in such a floated state, the glass sheet 18 is transferredover the in-furnace beds 12, 15 toward the outlet 11 a of the heatingfurnace 11, whereupon the glass sheet 18 is gradually bent into theshape of a single-curved glass sheet 18 a, which is complementary withthe shapes of the upper surfaces 13, 16 of the in-furnace beds 12, 15.

[0054] As is apparent from FIG. 1, the bend-shaping apparatus 10 alsoincludes a cooling bed 20 disposed externally of the outlet 11 a of theheating furnace 11 proximately to the latter (hereinafter called“out-furnace bed”). As the single-curved glass sheet 18 a is transferredpast the outlet 11 a onto the out-furnace bed 20, the glass sheet 18 ais bent in a direction of its transfer, thereby providing a dual-curvedglass sheet 18 b. Cooling air is then jetted, as indicated by arrows,from an upper surface 21 of the out-furnace bed 20 to cool the glasssheet 18 b supported in a floated state.

[0055] The glass sheet floating over the upper surfaces 13 of thein-furnace beds 12, the upper surface 16 of the in-furnace bed 15 andthe upper surface 21 of the out-furnace bed 20 is transferred over thebeds 12, 15, 20 in a direction of its transfer by a transfer mechanismnot shown.

[0056] In the bend-shaping apparatus 10, at least that one 15 of thein-furnace beds 12, 15 which is positioned proximate to the outlet 11 aof the heating furnace 11 has a downstream end 15 a elevated to providean uphill. An upstream end 20 a of the out-furnace bed 20 is elevated toform a downhill. Opposed ends of the in- and out-furnace beds 15, 20 canthus be lifted to jointly form a hill by means of an elevating mechanism30.

[0057] Next, the upper surfaces 16, 13 of the in-furnace beds 15, 12will be discussed in detail.

[0058] The upper surface 16 of the in-furnace bed 15 is curved in atransverse direction to provide a ridge line 16 a extending verticallycentrally thereof. The upper surface 16 also has a multiplicity of airjet holes 17 for jetting hot air against a lower surface of the glasssheet 18 to cause the glass sheet to float over an entire area of theupper surface 16.

[0059] The upper surface 13 of the in-furnace bed 12 is transverselycurved with a curvature which is substantially zero at its portionproximate to an inlet of the heating furnace 11 but increasesprogressively toward the outlet 11 a of the heating furnace 11. Beingthus curved, the upper surface 13 has a ridge 13 a extending linearlycentrally along the length thereof. The upper surface 13 also has amultiplicity of hot air jet holes 14 for jetting hot air against a lowersurface of the glass sheet 18 to cause the glass sheet to float over anentire area of the upper surface 13. The in-furnace bed 12 positionedproximate to the heating furnace outlet 11 a may have an upper surfaceconstructed similarly to the upper surface 16 of the in-furnace bed 15.

[0060] As already explained, the out-furnace bed 20 is disposedproximately to the outlet 11 a of the heating furnace 11. The uppersurface 21 of the out-furnace bed 20 is constructed similarly to theupper surface 16 of the in-furnace bed 15 and has a multiplicity of airjet holes 22 for jetting cold air to cool the glass sheet 18 whilefloating supporting the latter. The upper surface 21 is transverselycurved to provide a linear ridge 21 a extending centrally along thelength thereof.

[0061] By virtue of the upper surfaces 16, 21 thus curved in a lateraldirection and their respective ridges 16 a, 21 a extending linearly in adirection of glass transfer, the beds for manufacturing a single-curvedglass sheet may be used also for manufacturing a dual-curved glasssheet. That is, the dual-curved glass sheet manufacture is enabled byoperating the elevating mechanism 30 to raise the downstream end 15 a ofthe in-furnace bed 15 and the upstream end 20 a of the out-furnace bed20 such that the in- and out-furnace beds 15, 20 jointly form a hillsloped in a direction of glass transfer. For bend-shaping thesingle-curved glass sheet 18 a with the in- and out-furnace beds 15, 20,the downstream and upstream ends 15 a, 20 a of the beds 15, 20 may bebrought down to their original positions by means of the elevating means30.

[0062] As can be appreciated from FIG. 1, the elevating means 30comprises a first elevating mechanism 31 for vertically moving thedownstream and upstream ends 15 a and 15 b of the in-furnace bed 15 anda second elevating mechanism 32 for vertically moving the upstream anddownstream ends 20 a and 20 b of the out-furnace bed 20. The firstelevating mechanism 31 and the second elevating mechanism 32 have thesame construction. Thus, in the following discussion, only the secondelevating mechanism 32 will be referenced and discussion as to the firstelevating mechanism 31 will be omitted.

[0063] Reference is now made to FIG. 2 illustrating in explodedperspective the glass bend-shaping apparatus according to the presentinvention, in particular relation with the out-furnace bed 20 and thesecond elevating mechanism 32.

[0064] As shown in FIG. 2, the second elevating mechanism 32 comprises ajack unit 33 for vertically moving the upstream and downstream ends 20a, 20 b of the out-furnace bed 20, and a slide mechanism 60 disposedbetween the jack unit 33 and the out-furnace bed 20.

[0065] The jack unit 33 comprises a pair of front jacks 34, 34 and apair of rear jacks 44, 44, each disposed on respective support bases 25,25. The front jacks 34, 34 are operatively connected via a front driverod 35 having at one end thereof an operation handle 36 for operatingthe front jacks 34, 34. Similarly, the rear jacks 44, 44 are operativelyconnected via a rear drive rod 45 having at one end thereof a rearoperation handle 46 for operating the rear jacks 44, 44. The front jacks34, 34 include respective lifting rods 37, 37 having upper endsconnected to a table 52 via a front connecting portion 40. Similarly,the rear jacks 44, 44 include respective lifting rods 47, 47 havingupper ends connected to the table 52 via a rear connecting portion 50.

[0066] The connecting portion 40 includes brackets 41, 41 connected tothe respective upper ends of the lifting rods 37, 37 by means of pins 40a, 40 a, guides 42, 42 connected to the respective guides 42, 42, andrails 43, 43 mounted to an inlet end 52 a of the table 52 and slidablyreceived in the respective guides 42, 42.

[0067] Similarly, the connecting portion 50 includes brackets 51, 51connected to the respective upper ends of the lifting rods 47, 47 bymeans of pins 50 a, 50 a and to an outlet end 52 b of the table 52.

[0068] In the jack unit 33, by turning the operation handle 36 to causethe front drive rod 35 to turn clockwise or counterclockwise, thelifting rods 37, 37 simultaneously move vertically upwardly to therebylift the inlet end side of the table 52. By turning the rear operationhandle 46 to cause the rear drive rod 45 to turn clockwise orcounterclockwise, the lifting rods 47, 47 simultaneously move verticallyupwardly to thereby lift the outlet end side of the table 52.

[0069] By virtue of the guides 42, 42 and rails 43, 43 provided at thefront connecting portion 40, positional displacement of the table 52,which occurs when the table 52 is inclined, can be adjusted or cured.

[0070] The table 52 comprises right and left frames 53, 54 having inletside ends interconnected by an inlet side frame 55 and outlet side endsinterconnected by an outlet side frame 56 such that it has a rectangularconfiguration. The right and left frames 53, 54 have through-holes 53 a,54 a for supporting a rotary shaft 61 of the slide mechanism 60.

[0071] The rotary shaft 61 of the slide mechanism 60 has pinions 62, 62provided at opposed ends thereof. The rotary shaft 61 is supported onthe right and left frames 53, 54 with the opposed ends rotatablyreceived in the respective through-holes 53 a, 54 a. The rotary shaft 61also includes a spline 61 a meshed with a reduction gear 63 disposedsidewardly of the right frame 53. The reduction gear 63 includes a driveshaft 64 having an operational handle at its end remote from thereduction gear 63. The right and left pinions 62 are brought intomeshing engagement with respective racks 66, 66 carried on guides 67, 67mounted to an underside of the out-furnace bed 20. The guides 67, 67 aremounted to rails, not shown, of an underside of the out-furnace bed 20.The guides 67, 67 are also slidably disposed on rails, not shown, of theright and left frames 53, 54.

[0072] In the slide mechanism 60, by turning the operational handle 65,the rotary shaft 61 is turned together with the pinions 62, 62 to causethe right and left racks 66, 66 to move horizontally. This causes theout-furnace bed 20 to move horizontally through the guides 67, 67.

[0073] As a result, a space between the downstream end 15 a of thein-furnace bed 15 and the upstream end 20 a of the out-furnace bed 20becomes small, thereby achieving smooth transfer of the glass sheet 18from the in-furnace bed 15 to the out-furnace bed 20.

[0074] With reference to FIG. 3A to FIG. 5, discussion will be made nextas to a method for bend-shaping the glass sheet in the bend-shapingapparatus 10.

[0075] Referring now to FIG. 3A, with the in-furnace bed 15 and theout-furnace bed 20 laid flat by operating the first and second elevatingmechanisms 31, 32 (FIG. 1), the glass sheet 18 is shaped into a curvedshape. That is, the glass sheet 18 is floatingly supported over thein-furnace bed 15 by hot air jetted as arrowed from the upper surface 13of the in-furnace bed 15 and is then transferred in such a state alongthe in-furnace bed 12. The glass sheet 18 is then heated to a softeningpoint in the heating furnace 11 so that it becomes a single-curved glasssheet 18 a bent by its own weight to conform to the upper surface 16 ofthe in-furnace bed 15.

[0076] Then, the glass sheet 18 a is pulled out from the heating furnace11 and transferred onto the out-furnace bed 20, where it is floatinglysupported thereover by cold air jetted from the surface 21 of theout-furnace bed 20 against a lower surface thereof and cooled down bycooling air jetted as arrowed from a cooling unit 70 against an uppersurface of the glass sheet 18 a, thereby forcedly air quenching theglass sheet 18 a.

[0077] Turning now to FIG. 3B, the downstream end 15 a of the in-furnacebed 15 is lifted as shown by arrow A by turning the rear operationalhandle 46 (see FIG. 1) of the first elevating mechanism 31 to apredetermined position. Then, the upstream end 15 b of the in-furnacebed 15 is lifted by turning the front operational handle 36 of the firstelevating mechanism 31 up to a position as high as the in-furnace bed12.

[0078] Next, the upstream end 20 a of the out-furnace bed 20 is liftedas shown by arrow B by turning the front operational handle 36 (FIG. 1)of the second elevating mechanism 32 up to a position as high as thedownstream end 15 a of the in-furnace bed 15. Thereafter, the downstreamend 20 b of the out-furnace bed 20 is lifted by turning the rearoperational handle 46 of the second elevating mechanism 32 up to aposition as high as a transfer table 72.

[0079] After height adjustment of the in- and out-furnace beds 15, 20 asdescribed above is completed, that side of the cooling unit 70 proximateto the heating furnace 11 is elevated as shown by arrow C. Height of thecooling unit 70 may be set to be applicable for both single-curved glasssheet manufacture process and dual-curved glass sheet manufactureprocesses so that operations for lifting the cooling unit 70 can beomitted.

[0080] Referring now to FIG. 4A, the in- and out-furnace beds 15, 20 arelaid in an angled fashion, that is, to form a hill, with a relativelylarge space S1 left therebetween. The cooling unit 70 may be inclined incorrespondence with the out-furnace bed 20.

[0081] In this state, the operational handle 65 (see FIG. 1) of thefirst elevating mechanism 31 is turned to cause the in-furnace bed 15 toslide in a direction shown by arrow D. This is followed by turning theoperational handle 65 (see FIG. 1) of the second elevating mechanism 32to cause the out-furnace bed 20 to slide in a direction shown by arrowE. Such sliding of the in- and out-furnace beds 15, 20 makes the spacebetween those beds 15, 20 as small as S2, as shown in FIG. 4B.

[0082] Turning now to FIG. 5, the glass sheet 18 is floatingly supportedover the in-furnace bed 12 by hot air jetted from the upper surface 13of the in-furnace bed 12 as arrowed and is transferred in such a statealong the in-furnace bed 12. While being held in such a state, the glasssheet 18 is heated in the heating furnace 11 to a softening temperatureso that the glass sheet 18 can be bent by its own weight into asingle-curved glass sheet 18 a conforming to the shape of the uppersurface 13 of the in-furnace bed 12.

[0083] Upon transfer of the thus-formed single-curved glass sheet 18 afrom the downstream end 15 a of the in-furnace bed 15 onto theout-furnace bed 20, since the in-furnace bed 15 and the out-furnace bed20 are laid in an angled fashion, that is, to form a hill, thesingle-curved glass sheet 18 a is bent by its own weight in a directionof its transfer or a longitudinal direction. This provides a dual-curvedglass sheet 18 b bent in two directions, namely, transverse andlongitudinal directions.

[0084] The thus-formed dual-curved glass sheet 18 b is transferred ontothe out-furnace bed 20. At this time, the in-furnace bed 15 and theout-furnace bed 20 are slidingly moved to come closer to each other tomake the space between the downstream end 15 a of the in-furnace bed 15and the upstream end 20 a of the out-furnace bed 20 as small as possibleso that the glass sheet can be transferred smoothly from the in-furnacebed 15 to the out-furnace bed 20, thereby preventing a lower surface ofthe glass sheet from being scratched.

[0085] After the glass sheet 18 b is transferred onto the out-furnacebed 20, cold air is jetted as arrowed from the upper surface 21 of theout-furnace bed 20 to floatingly support the glass sheet 18 b over theout-furnace bed 20. At the same time, cooling air is jetted from thecooling unit 70 against an upper surface of the glass sheet 18 b toforcedly air quench the glass sheet 18 b. The thus-quenched glass sheet18 b is further cooled down by atmospheric air while it is transferredby means of the transfer table 72. By such air quenching, thedual-curved glass sheet 18 b is made to retain its dual-curved shape andis tempered.

[0086] In the glass sheet bend-shaping method described in relation toFIG. 3A to FIG. 5, the in-furnace bed 15 and the out-furnace bed 20 havetheir upper surfaces 16, 21 bent in a transverse direction andridgelines 16 a, 21 a extending linearly. This enables shaping of theglass sheet 18 into the single-curved glass sheet by arranging the in-and out-furnace beds 15, 20 to lie horizontally.

[0087] By elevating the downstream end 15 a of the in-furnace bed 15 andthe upstream end 20 a of the out-furnace bed 20 to a predeterminedheight, shaping of the glass sheet 18 into the dual-curved glass sheetis enabled. Consequently, by simple operations such as adjusting theheights of the downstream end 15 a of the in-furnace bed 15 and theupstream end 20 a of the out-furnace bed 20, both the single-curvedglass sheet 18 and the dual-curved glass sheet 18 b can be manufactured.

[0088] Discussion will be made next as to the radius of curvature of thedual-curved glass sheet in a direction of its transfer with reference toFIGS. 6 to 9.

[0089] In FIG. 6, the bend-shaping apparatus of the present invention isshown in schematic side elevation with dimensions of components thereof.The dual-curved glass sheet 18 b has a radius of curvature C taken in adirection of its transfer. The radius of curvature C is determined byapparent bed radius of curvature R, which in turn is determined bylengths L1, L2 of the beds 15, 20, inclination heights H of the beds 15,20, and a length G of the glass sheet 18. The term “inclination height”represents a height from an original flat position to an elevatedposition of the beds, as shown by H in FIG. 6. Relations between thesedetermining factors will be described with reference to graphs later on.

[0090] In the embodiment being described, L1 is set to be equal to L2.Thus, the bed lengths L1 and L2 will be represented below simply by Lfor clarity. Note also that the following description will be made as toan example wherein a single one of each of the in-furnace bed 15 andout-furnace bed 20 is used to form a hill. Alternatively, pluralin-furnace beds 15 and out-furnace beds 20 may be used to form such ahill, in which instance the entire length of whole beds shouldcorrespond to the bed length L. Desirably, the glass length G and bedlength L are set to be G<L.

[0091] Reference is now made to the graph of FIG. 7 showing a relationbetween the apparent bed radius of curvature R and bed inclinationheight H, wherein the beds 15, 20 have a length L of 750 mm. Theapparent bed radius of curvature R (mm) is shown on the vertical axiswhile the bed inclination height H (mm) is shown on the horizontal axis.The solid line indicates the glass sheet having a length of 300 mm. Thebroken line represents the glass sheet having a length of 500 mm. Thedouble-dot-and-single-dash line indicates the glass sheet having alength of 750 mm.

[0092] Assume that each bed has an inclination height H of, e.g., 5 mm.Then, the apparent bed radius of curvature R is expressed by:

[0093] R=12×10³ mm, where the glass sheet has a length G of 300 mm;

[0094] R=18×10³ mm, where the glass sheet has a length G of 500 mm; and

[0095] R=26×10³ mm, where the glass sheet has a length G of 750 mm.

[0096] That is, the larger the glass sheet length G becomes, the largerthe apparent bed radius of curvature R becomes. As a result, thecurvature of the dual-curved glass sheet 18 b becomes small.

[0097] In the case where the glass sheet length G is 750 mm, theapparent bed radius of curvature R is 15×10³ mm when the bed inclinationheight H is 10 mm. The apparent bed radius of curvature R is 26×10³ mmwhen the bed inclination height H is 5 mm. That is, the larger the bedinclination height H becomes larger, the smaller the apparent bed radiusof curvature R becomes. As a result, the curvature of the dual-curvedglass sheet 18 b becomes larger.

[0098] Reference is made next to the graph of FIG. 8 showing a relationbetween the apparent bed radius of curvature R and the bed inclinationheight H when the beds 15, 20 are 1,000 mm long. The apparent bed radiusof curvature R (mm) is shown on the vertical axis while the bedinclination height H (mm) is shown on the horizontal axis. The solidline indicates the glass sheet having a length of 300 mm. The brokenline represents the glass sheet having a length of 500 mm. Thedouble-dot-and-single-dash line indicates the glass sheet having alength of 700 mm. The single-dot-and-single-dash line represents theglass sheet having a length of 1,000 mm.

[0099] Assume that each bed has an inclination height H of, e.g., 5 mm.Then, the apparent bed radius of curvature R is expressed by:

[0100] R=15×10³ mm, where the glass sheet length G is 300 mm;

[0101] R=25×10³ mm, where the glass sheet length G is 500 mm; and

[0102] R=35×10³ mm, where the glass sheet length G is 700 mm.

[0103] That is, similarly to the case of FIG. 7, the larger the glasssheet length G becomes, the larger the apparent bed radius of curvatureR becomes. As a result, the curvature or the curve of the dual-curvedglass sheet 18 b becomes small.

[0104] Now, taking the bed inclination height H of 5 mm, as an example,comparison is made between the apparent bed radius of curvature R in thecase where a bed length L is 700 mm (the graph of FIG. 7) and theapparent bed radius of curvature R in the case where a bed length L is1,000 mm (the graph of FIG. 8).

[0105] When the glass sheet length G is 300 mm, the apparent bed radiusof curvature R is 12×10³ mm in the case where the bed length L is 750 mmwhile this is 15×10³ mm in the case where the bed length L is 1,000 mm.When the glass sheet length G is 500 mm, the apparent bed radius ofcurvature R is 18×10³ mm in the case where the bed length L is 750 mmwhile this is 25×10³ mm in the case where the bed length L is 1, 000 mm.Thus, with the bed inclination height H kept the same, the smaller thebed length L becomes, the smaller the apparent bed radius of curvature Rbecomes, causing the curvature of the dual-curved glass sheet 18 b togrow larger.

[0106] In the glass sheet having the length G of 700 mm as shown in thegraph of FIG. 8, the apparent bed radius of curvature R is 15×10³ mmwhen the bed inclination height H is 10 mm and is 26×10³ mm when the bedinclination height H is 5 mm. That is, the larger the bed inclinationheight H becomes, the smaller the apparent bed radius of curvature Rbecomes, causing the curvature of the dual-curved glass sheet 18 b togrow larger.

[0107] As can be appreciated from the discussion just made and thegraphs of FIGS. 7 and 8, the apparent bed radius of curvature R isdetermined by the lengths L and inclination heights H of the beds 15, 20and the glass sheet length G. Although the foregoing discussion has beenmade in relation to the case where the in- and out-furnace beds 15, 20have the same length L, the same can be applied to the case where thein- and out-furnace beds 15, 20 have different lengths.

[0108] Reference is made next to the graph of FIG. 9 showing a relationbetween the apparent bed radius of curvature R and the radius ofcurvature C of the glass sheet. In the graph, the apparent bed radius ofcurvature R (mm) is shown on the vertical axis while glass sheet radiusof curvature C (mm) is shown on the horizontal axis.

[0109] From the graph, it can be appreciated that the relation expressedby R=0.43×C+12.8×10³ (Expression 1) is established. The unit used hereinis mm.

[0110] Consequently, for manufacturing a dual-curved glass sheet havingthe radius of curvature C of, e.g., 100×10³ mm, the apparent bed radiusof curvature R may be set to be R=55.8×10³ mm. Similarly, formanufacturing a dual-curved glass sheet having a radius of curvature Cof 200×10³ mm, the apparent bed radius of curvature R may be set to beR=98.8×10³ mm.

[0111] By thus adjusting the apparent bed radius of curvature R, theradius of curvature C of the glass sheet is determined. In other words,adjustment of the apparent bed radius of curvature R enables adjustmentsuch that the desired bending of the glass sheet in the direction oftransfer of the glass sheet can be achieved. In addition, by getting therelation of Expression 1 readied in advance, it becomes possible toreadily obtain the apparent bed radius of curvature R corresponding tothe radius of curvature C of the glass sheet.

[0112] The relation of Expression 1, that is, R=0.43×C+12.8×10³ mm,becomes possible when the radius of curvature C of the glass sheet fallsin a range of 10×10³ mm<C<∞. Curvature of the glass sheet is representedas a reciprocal (1/C) of the glass sheet radius of curvature C and fallsin a range of 0<(1/C)<1×10⁻⁴ mm⁻¹ (Expression 2).

[0113] 0<(1/C) is used herein because the glass sheet radius ofcurvature C becomes ∞ (infinite) when (1/C)=0, resulting in theproduction of a single-curved glass sheet linear in the direction of itstransfer. Thus, 0<(1/C) is required for the production of a dual-curvedglass sheet. The reason for the adoption of (1/C)<1×10⁻⁴ mm⁻¹ is that if(1/C)≧1×10⁻⁴ mm⁻¹ is used in its stead, the glass sheet radius ofcurvature C becomes smaller than 1×10⁴ mm. This makes the bedinclination too excessive and smooth transfer of the glass sheetdifficult to achieve. There is also a fear that the lower surface of theglass sheet may be scratched by interfering with the beds laid in anangled fashion. Further, it may also become difficult to smoothly bendthe glass sheet in the direction of its transfer. Thus, the verticalmovement of the beds is restricted to (1/C)<1×10⁻⁴ mm⁻¹.

[0114] In the preferred embodiment explained thus far in relation toFIGS. 7 to 9, the relation between the inclination height H of the in-and out-furnace beds 15, 20 and the apparent bed radius of curvature Rand the relation between the apparent bed radius of curvature R and theglass sheet radius of curvature C are obtained in advance. This makes itpossible to determine the inclination height H of the in- andout-furnace beds 15, 20 for eventually obtaining the desired radius ofcurvature C of the glass sheet. Consequently, the inclination height Hof the beds 15, 20 can be readily obtained in correspondence with theglass sheet radius of curvature C. As a result, the desired glass sheetradius of curvature C can be readily obtained.

[0115] In the graph of FIG. 9, the glass sheet radius of curvature C isshown to fall in the range of 10×10³ mm to 300×10³ mm. However, in themethod and apparatus according to the present invention, it is possibleto manufacture a dual-curved glass sheet with a radius of curvature C inthe direction of transfer of the glass sheet, ranging from 10×10³ mm to∞ mm. An infinite (∞) is applicable to a single-curved glass sheet.

[0116] Discussion will be made next as to second to fifth embodiments ofthe present invention with reference to FIG. 10A to FIG. 14. Throughoutthese Figures, like components will be designated by like referencenumerals and their description will be omitted.

[0117] As shown in FIG. 10A, a bend-shaping apparatus 80 according tothe second embodiment of the present invention includes an in-furnacebed 81 and an out-furnace bed 85, which are laid flat. These beds 81, 85have respective downstream end surface 82 and upstream end surface 86,which are opposed to each other. The downstream end surface 82 of thein-furnace bed 81 has a curved configuration and is chamfered at a lowercorner thereof. Similarly, the upstream end surface 86 of theout-furnace bed 85 has a curved configuration and is chamfered at alower corner thereof. Other parts and components are identical to thoseof the bend-shaping apparatus 10 according to the first embodiment.

[0118] Chamfering the lower corner of the downstream end surface 82 ofthe in-furnace bed 81 makes the end surface 82 acutely angled asindicated by e with respect to an upper surface 84 of the bed 81.Similarly, chamfering of the lower corner of the upstream end surface 86of the out-furnace bed 85 makes the end surface 86 acutely angled asindicated by e with respect to an upper surface 88 of the bed 85.

[0119] This makes it possible to raise the downstream end surface 82 ofthe in-furnace bed 81 and to avoid interference which occurs between thedownstream end surface 82 of the in-furnace bed 81 and the upstream endsurface 86 of the out-furnace bed 85 when the upstream end surface 86 iselevated. As a result, it becomes possible to make a space S3 betweenthe downstream end surface 82 and the upstream end surface 86 small, asshown in FIG. 10B. Since the dual-curved glass sheet 18 b can thus betransferred smoothly from the in-furnace bed 81 to the out-furnace bed85, the lower surface of the dual-curved glass sheet 18 b can beprevented from being scratched during transfer.

[0120] Turning now to FIG. 11, a bend-shaping apparatus 90 according tothe third embodiment of the present invention includes a guide roll 91disposed in the space defined between the in-furnace bed 15 and theout-furnace bed 20 for guiding the dual-curved glass sheet 18 b. Apartfrom the guide roll 91, the apparatus 90 is constructed identically tothe apparatus 10 according to the first embodiment. Provision of theguide roll 91 enables guided smooth transfer of the dual-curved glasssheet 18 b from a downstream end of the in-furnace bed 15 onto theout-furnace bed 20. As a result, damaging of the lower surface of theglass sheet 18 b can be prevented.

[0121] More specifically, the guide roll 91 is arranged such that it canbe vertically moved by an elevating means, not shown, to correspond orharmonize with the elevated in- and out-furnace beds 15, 20. The guideroll 91 may be detachably mounted to the apparatus so that it can bedetached when the in- and out-furnace beds 15, 20 are laid flat. Theguide roll 92 may be heated so as to prevent the dual-curved glass sheet18 b from being cooled thereby.

[0122] As shown in FIG. 12, a bend-shaping apparatus 95 according to thefourth embodiment of the present invention includes an air jet nozzle 96disposed in the space between the in-furnace bed 15 and the out-furnacebed 20 for jetting air against the dual-curved glass sheet 18 b to guidethe latter. Other than the air jet nozzle 96, the apparatus 95 isconstructed identically to the apparatus 10 according to the firstembodiment.

[0123] With the in- and out-furnace beds 15, 20 arranged in the form ofa chevron, there is a feat that in certain instances, a force forfloating the glass sheet may fall short. To cater to such instances, theair jet nozzle 96 is provided to jet air to assist in floating the glasssheet. As a result, with the assistance of the air jetted from thenozzle 96, the dual-curved glass sheet 18 b pulled past the downstreamend of the in-furnace bed 15 can be transferred smoothly onto theout-furnace bed 20. Consequently, the under surface of the glass sheet18 b can be prevented from being scratched during transfer.

[0124] The air jet nozzle 96 may be arranged such that it canselectively jet hot air and cooling air as needs arise. The air jetnozzle 96 is arranged such that it can be vertically moved by anelevating means, not shown, to be brought into correspondence orharmonization with the elevated state of the in- and out-furnace beds15, 20.

[0125] Next, reference is made to FIG. 13 illustrating a bend-shapingapparatus 100 according to the fifth embodiment of the presentinvention.

[0126] In the bend-shaping apparatus 100, an in-furnace bed 101 isdivided into five in-furnace bed pieces 102. These in-furnace bed pieces102 have upstream ends 102 a and downstream ends 102 b, which can beraised by an in-furnace elevating mechanism, not shown, to form anuphill.

[0127] Similarly, the out-furnace bed 104 is divided into fiveout-furnace bed pieces 105. These out-furnace bed pieces 105 haveupstream ends 105 a and downstream ends 105 b, which can be raised by anout-furnace elevating mechanism, not shown, to form a downhill. Otherthan these, the apparatus 100 is constructed identically to theapparatus 10 according to the first embodiment.

[0128] Since it is formed by the five in-furnace bed pieces 102, theuphill becomes gentle. Similarly, since it is formed by the fiveout-furnace bed pieces 105, the downhill becomes gentle. As a result,the dual-curved glass sheet 18 b can be transferred more smoothly,thereby preventing the glass sheet 18 b from being scratched at thelower surface thereof.

[0129] In the embodiment just described, the in-furnace bed 101 isdivided into the five in-furnace bed pieces 102 while the out-furnacebed 104 is divided into the five out-furnace bed pieces 105. However,the in- and out-furnace beds 101, 104 may be divided into an arbitrarynumber of pieces. For example, the in-furnace bed 101 may be dividedinto three in-furnace bed pieces while the out-furnace bed 104 may bedivided into two out-furnace bed pieces.

[0130] Referring now to FIG. 14, discussion will be made next as to abend-shaping apparatus according to the sixth embodiment of the presentinvention. The bend-shaping apparatus 110 includes a guide rollmechanism 111 provided in place of the guide roll 91 of the thirdembodiment (FIG. 11). Other than this, the apparatus 110 is constructedidentically to the apparatus 90 according to the third embodiment.

[0131] The guide roll mechanism 111 comprises a roll body 112 in theform of a rod which can be adjustably deformed into an arc-shape. Theguide roll mechanism 111 also includes a plurality of handles 113 andsupport rolls 114 whose height can be adjusted by operating the handles113 to thereby adjust the arc-shape of the roll body 112 to conform tothe shape of the dual-curved glass sheet 18 b (FIG. 11).

[0132] This arrangement produces the same results as produced by theapparatus according to the third embodiment. Further, since thedual-curved glass sheet 18 b is fully supported transversely by theguide roll mechanism 111, the glass sheet can be transferred moresmoothly onto the out-furnace bed 20. As a result, the dual-curved glasssheet 18 b can be prevented from being scratched at its under surface.

[0133] The guide roll mechanism 111 is arranged such that it can bevertically moved by an elevating mechanism, not shown, to conform to theelevated state of the in- and out-furnace beds 15, 20. Further, theguide roll mechanism 111 is detachably mounted to the apparatus so thatit can be detached when the in- and out-furnace beds 15, 20 are laidflat. The guide roll mechanism 111 may be heated so as to prevent theglass sheet 18 b from being cooled during transfer thereover.

[0134] In the above-described embodiments, both the downstream end 15 aand upstream end 15 b of the in-furnace bed 15 is elevated by the firstelevating mechanism 31. Alternatively, arrangements may be made to raiseonly the downstream end 15 a of the in-furnace bed 15. Similarly,although both the upstream end 20 a and downstream end 20 b of theout-furnace bed 20 are elevated by the second elevating mechanism 32 inthose embodiments, arrangements may be made alternatively to raise onlythe upstream end 20 a of the out-furnace bed 20.

[0135] In the above-described embodiments, although the first and secondelevating mechanisms 31, 32 have been described to be hand-operated, themechanisms 31, 32 may be arranged to be hydraulically or pneumaticallyoperated.

[0136] Both the in- and out-furnace beds 15, 20 have been described tobe slidingly moved by the slide mechanism 60 in the above-describedembodiments. Alternatively, only one of those beds 15, 20 may bearranged to be slidingly moved.

[0137] Obviously, various minor changes and modifications of the presentinvention are possible in the light of the above teaching. It istherefore to be understood that within the scope of the appended claims,the invention may be practiced otherwise than as specifically described.

What is claimed is:
 1. An apparatus for bend-shaping a glass sheet,comprising: a heating furnace for heating the glass sheet, transferredtherethrough along a path of travel thereof, to a substantiallysoftening temperature of the glass sheet, said heating furnace having aninlet positioned upstream of said path of travel and an outletpositioned downstream of said path of travel; a plurality of in-furnacebeds disposed within said heating furnace, each of said in-furnace bedshaving an upper surface of upwardly convex shape with a curvatureincreasing progressively toward said outlet of said heating furnace,said upper surfaces being designed to jet hot air against the glasssheet to support the glass sheet in a floated state thereover such thatthe glass sheet bends transversely by own weight thereof complementarilyto the shape of said upper surfaces; at least one out-furnace beddisposed externally of said heating furnace proximately to said outletof said heating furnace, said out-furnace bed having an upper surface ofupwardly convex shape, said in-furnace beds and said out-furnace bedbeing arranged linearly along said path of travel; and an elevatingmechanism, disposed below a downstream end of that one of saidin-furnace beds which is positioned proximately to said outlet of saidheating furnace and below an upstream end of said out-furnace bed, forelevating said downstream end of said one in-furnace bed and saidupstream end of said out-furnace bed to cause said one in-furnace bedand said out-furnace bed to form a hill sloped in a direction along saidpath of travel, so that upon passage over said hill, the glass sheetbends longitudinally by own weight thereof complementarily to the shapeof said hill, said upper surface of said out-furnace bed being designedto jet cold air against the glass sheet transferred past said outlet ofsaid heating furnace to cool down the glass sheet while supporting thesame in a floated state thereover.
 2. An apparatus for bend-shaping aglass sheet, according to claim 1, further comprising a slide mechanismfor sliding at least one of said one in-furnace bed and said out-furnacebed in said direction along said path of travel of the glass sheet. 3.An apparatus for bend-shaping a glass sheet, according to claim 1,wherein said one in-furnace bed has a downstream end surface of curvedconfiguration, and said out-furnace bed has an upstream end surface ofcurved configuration.
 4. An apparatus for bend-shaping a glass sheet,according to claim 1, wherein said downstream end surface of said onein-furnace bed has a lower corner, and said upstream end surface of saidout-furnace bed has a lower corner, at least one of said lower cornersof said downstream and upstream end surfaces being chamfered.
 5. Anapparatus for bend-shaping a glass sheet, according to claim 1, furthercomprising a guide roll, disposed in a space defined between said onein-furnace bed and said out-furnace bed, for guiding the glass sheetalong said path of travel.
 6. An apparatus for bend-shaping a glasssheet, according to claim 5, wherein said guide roll has a curvedconfiguration conforming to the curved shape of the glass sheet.
 7. Anapparatus for bend-shaping a glass sheet, according to claim 1, furthercomprising an air jet nozzle, disposed in a space defined between saidone in-furnace bed and said out-furnace bed, for jetting air against theglass sheet to thereby guide the latter along said path of travel.
 8. Amethod for bend-shaping a glass sheet in a bend-shaping apparatusincluding a heating furnace having an outlet positioned downstream of apath of transfer of the glass sheet, a plurality of in-furnace bedsdisposed within said heating furnace, at least one out-furnace beddisposed externally of said heating furnace proximately to said outletin end to end relation to that one of said in-furnace beds which ispositioned proximately to said outlet, said in-furnace beds and saidout-furnace bed having upper surfaces curved transversely, said methodcomprising the steps of: elevating a downstream end of said onein-furnace bed and an upstream end of said out-furnace bed to apredetermined bed inclination height H so that said one in-furnace bedand said out-furnace bed jointly form a hill which allows to impart adesired radius of curvature C to the glass sheet, said bed inclinationheight H being obtained by first determining a first relation betweenthe bed inclination height H and an apparent bed radius of curvature Ron a basis of a length L1 of said one in-furnace bed forming an uphillof said hill, a length L2 of said out-furnace bed forming a downhill ofsaid hill, the bed inclination height H, and a length G of the glasssheet in a direction of transfer thereof, and then determining a secondrelation between the apparent bed radius of curvature R and the desiredradius of curvature C of the glass sheet; heating the glass sheet insaid heating furnace to a substantially softening temperature of theglass sheet and jetting hot air from said upper surfaces of saidin-furnace beds to floatingly support the glass sheet in such a manneras to allow the glass sheet to bend by own weight thereof transverselycomplementarily to the shape of the transversely curved in-furnace beds;transferring the transversely bent glass sheet over said hill so thatthe glass sheet bends longitudinally complementarily to the shape of thehill sloped in said direction of transfer; and transferring thebi-directionally bent glass sheet past said outlet onto said out-furnacebed and jetting cold air from said upper surface of said out-furnace bedto cool the bi-directionally bent glass sheet while supporting thelatter in a floated state.
 9. A method for bend-shaping a glass sheet,according to claim 8, wherein curvature (1/C) represented as areciprocal of the glass sheet radius of curvature C falls in a range of0<(1/C)<1×10⁻⁴ mm⁻¹ mm⁻¹.
 10. A method for bend-shaping a glass sheet,according to claim 8, wherein the relation between said apparent bedradius of curvature R and said glass sheet radius of curvature C isrepresented by R=0.43×C+12.8×10³ (unit: mm).
 11. A method forbend-shaping a glass sheet, according to claim 8, wherein the cooling ofthe glass sheet over said out-furnace bed comprises air quenching theglass sheet.